Valves
| Characteristic | Meaning |
Eccentricity of valve stems relative to working chamfer, no more than, mm | 0,03 |
Chamfer angle | 45° + 15' |
Minimum height of valve head to working chamfer M 102, not less than, mm | |
| 1,0 |
| 2,0 |
Valve characteristics
Parameter, mm | Engine model | |||
M 115.938 | M 102.920, M 102.939 | M 102.980, M 102.982 | M 115.954 | |
| Width of the working chamfer of the valve | ||||
| 1,8—2,5 | |||
| 1,5—2,5 | |||
| Nominal valve head recess | ||||
| 0,5 | 1,7 | 1,2 | 0,1 |
| 1,6 | 1,6 | 0,5 | 1,6 |
| Maximum permissible valve recess | ||||
| 1,5 | 2,6 | 2,1 | 0,9 |
| 1,7 | 1,7 | 1,4 | 1,7 |
| Valve head diameter | ||||
| 44,30—44,10 | 39,90—40,10 | 39,90—40,10 | 47,10—46,90 |
| 37,25 | 35,90—36,10 | 37,25 | |
| Valve head height | ||||
| 1,0 | 1,6 | 1,6 | 1,0 |
| 1,5 | 2,7 | 2,7 | 1,5 |
| Valve stem diameter | ||||
| 8,948—8,970 | 7,970—7,955 | 8,955—8,970 | |
| 10,94—10,92 | 8,960—8,938 | 10,935—10,95 | |
| Valve stem length | ||||
| 128,0 | 114,7—115,10 | 128 | |
| 132,2 | 115,60—116,00 | 132,20 | |
Parameter, mm | M 123.920, M 123.921 | M 110.923 | M 110.984, M 110.988 | |
| Width of the working chamfer of the valve | ||||
| 1,8—2,5 | |||
| 1,5—2,5 | 1,5—2,0 | ||
| Nominal valve head recess | ||||
| 0,5 | 3,3 | 3,3 | |
| 1,5 | 0,6 | 0,6 | |
| Maximum permissible valve recess | ||||
| 1,5 | 4,2 | 4,2 | |
| 1,6 | 1,5 | 1,5 | |
| Valve head diameter | ||||
| 41,30—41,10 | 45,10—45,30 | ||
| 37,00—37,20 | |||
| Valve head height | ||||
| 1,0 | 1,0 | 1,0 | |
| 2,0 | |||
| Valve stem diameter | ||||
| 8,955—8,970 | |||
| 10,935—10,95 | 10,94—10,96 | ||
| Valve stem length | ||||
| 128 | 115,0 | ||
| 132,20 | 118,00 | ||
Valve springs
The intake and exhaust valves have one identical spring for the M 102 and M 123 models and two springs for the M 110 and M 115 models. The valve springs of engines with adjustable clearances in the valve drive mechanism differ from the valve springs of engines with hydraulic clearance compensation. When assembling, direct the color mark to the valve spring plate.
Valve spring characteristics
Note: Color marking: Red - red; F-B - violet-white; J-K - yellow-brown; F-Kr. - violet-red; J-B - yellow-white.
Engine model | |||
M 115.938 | M 102.920, M 102.939 | M 102.980, M 102.982 | M 115.954 |
Kr. |
| F—K/F—Kr. | Kr. |
M 123.920, M 123.921 | M 110.923 | M 110.984, M 110.988 | |
F—Kr. | — | — | |
Spring diameter
Parameter, mm | Engine model | |||
M 115.938 | M 102.920, M 102.939 | M 102.980, M 102.982 | M 115.954 | |
| Spring diameter | ||||
| 33,2—33,7 | 33,9 | 34,2 | 33,1—33,4 |
| 22,2 | — | — | 22,29 |
| Spring wire diameter | ||||
| 4,3 | 4,6 | 4,75 | 4,25 |
| 2,5 | — | — | 2,5 |
| Spring diameter in free state | ||||
| 50,0 | 48,5 | 49,0 | 50,0 |
| 45,0 | — | — | 45,0 |
| Length and load of the outer spring | ||||
| length, mm / under load, kgf | 30,0/66,7—76,3 | 30,4/79,0—85,0 | 30,5/84,3—90,2 | 30,0/66,7—76,3 |
| rated load, kgf | 60,9 | 71,0 | 76,0 | — |
| Length and load of the inner spring | ||||
| length, mm / under load, kgf | 21,0/22,8—25,2 |
| — | 21,0/22,8—25,2 |
| rated load, kgf | 20,5 |
| — | 20,5 |
| Spring catalog number | ||||
| 1290530220 | — | — | 1290530320 |
| 1080530022 | — | — | 1080530022 |
Parameter, mm | M 123.920, M 123.921 | M 110.923 | M 110.984, M 110.988 | |
| Spring diameter | ||||
| 34,1—34,5 | 33,8—34,1 | ||
| — | 22,0—22,4 | ||
| Spring wire diameter | ||||
| 4,75 | 4,6 | 4,6 | |
| — | 2,5 | 2,5 | |
| Spring diameter in free state | ||||
| 49,0 | 49,5 | ||
| — | 45,0 | ||
| Length and load of the outer spring | ||||
| length, mm / under load, kgf | 30,5/86,0—92,0 | 30,5/84,0—92,0 | ||
| rated load, kgf | 57,1 | — | — | |
| Length and load of the inner spring | ||||
| length, mm / under load, kgf | — | 21,5/22,8—25,2 | ||
| rated load, kgf | — | 20,5 | ||
| Spring catalog number | ||||
| 1230530020 | 1180530120 | ||
| — | 1300530222 | ||
Valve drive rocker arms
The rocker arms are made of steel and are the same for the inlet and outlet valves. The bearing surface of the rocker arm is surface hardened. The gap between the rocker arm and the valve stem is adjusted by turning the adjusting screw with a lock nut or compensated hydraulically. Oil enters the hydraulic tappet under pressure from the axle and the rocker arm stand.
| Characteristic | Meaning |
Inner diameter of rocker shaft, mm | 18,016—18,027 |
Rocker shaft diameter, mm | 17,989—18,000 |
| Radial clearance between rocker arm and axle, mm | 0,016—0,038 |
| Diameter of the hole in the camshaft support for the rocker arm stand, mm | 18,000—18,018 |
Hydraulic tappets
| Characteristic | Meaning |
Hydraulic compensation stroke, mm | 0,5—2,4 |
Thickness of mounting washers, mm | 0,9; 1,5; 1,8; 2,2 |
| Plate thickness, mm | 1,0; 1,5 |
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